Are you prepping food directly on the wood tops?

No - we will still use cutting boards

Also, they are made of rubber wood (if that matters). That's what the fabricator just told me.

https://generalfinishes.com/wood-finishes-retail/water-based-topcoats-and-sanding-sealer/flat-out-flat-water-based-topcoat Rubber wood is not a good choice for a furniture look wood top, or a top that you cut on. But this will be as close to "raw" as a finish can get in something that you can easily find.

@Nicholberry - You can technically use any water based polyurethane, if you let it fully cure. Note: fully cured is not the same thing as dry. You need to keep food off it for several weeks (3 or 4 depending).

I prefer to use a hardwax oil, Rubio Monocoat is my go to product. It is a tough finish with a flat sheen that is incredibly DIY friendly and, unlike polyurethane, it is infinitely repairable and is food safe.

There is a reason that everyone making ultra expensive slab counters and tables uses Rubio Monocoat. Hardwax oils are not cross-linked coatings and so you don’t have to deal with application problems. More importantly since they only bond to the wood, they can be spot sanded and repaired. However, they are not a maintenance free coating, every few years you will have to apply refresher to the top.